The present invention relates to earth working machinery and, more specifically, to an anchoring means for earth tunneling devices.
In laying pipelines, electric transmission lines, cable, etc, through road beds and other places where it is undesirable to dig a trench along the top of the earth, various tunneling devices have been developed.
These tunneling devices generally either drive a pipeline through the earth between trenches on each side of the earth section which is to be tunneled or a stem is first driven through the earth and then it is pulled back through the earth with the pipe attached thereto.
One common tunneling device which utilizes such a stem system is attached to a trenching machine known as a backhoe. Normally, this device is lowered into the ditch adjacent the earth section to be tunneled and by vertical up and down motion of the hydraulic lift system of the backhoe, the stem is forced through the earth to displace the stem sections into the earth under the road or other earth section which is to be tunneled.
The tunneling device, as it drives the stem into the earth, creates a counterreactive force which tends to force the device in a direction opposite to which the stems are driven. To prevent movement of the device in such opposite direction, several telescoping anchor arms, known as jacks, are attached to the device and extend from it to engage the earth bank so as to provide a back stop for the devices.
Upon each use, these jacks must be attached to the tunneling device, telescoped and locked into place against the earth bank. If the earth bank is not sufficiently solid enough to secure one or more of the jacks, the tunneling device will shift and become askew preventing further driving of the stem. After so shifting, the tunneling device must be realigned and the jacks reset which frequently requires pulling of the stem because of its askew position.
With such prior apparatus, after the stem is driven through the entire section of earth to be tunneled and before the stem is pulled back through the earth with the pipe, etc. attached thereto, the jacks must be repositioned on the opposite side of the tunneling device to provide a back stop for the device as it pulls on the pipe. The operation of these prior devices as above described obviously spells out many problems, including the inability to consistently drive the stems in a straight line. This causes breakage of equipment, misalignment of the pipe, and a very slow operation caused by the requirement to realign these tunneling devices and its associated jacks and also the complete removal and positioning of the jacks. Further, since frequently the ditch is filled with loose dirt, muck, or water, fouling of the tunneling device may result. Also, it is difficult with present equipment to feed the stems straight into the tunneling device.
Accordingly, there has been a long-felt need for improved means for anchoring tunneling devices as above described.